Most panel-like solar heat collectors presently on the market make use of a closed piping system soldered onto a metal sheet or sandwiched metal sheets with passageways fabricated therebetween. The first type of present solar heat collector panels involving a closed piping system is very expensive to manufacture due to the high cost of the pipes and the expense attributable to labor required in mounting the pipes on their supportive plate. The second sandwiched type of collector also involves expensive materials and high labor costs as well as sophisticated production machinery.
Examples of various forms of solar heat collector panels presently known are disclosed in U.S. Pat. Nos. 2,358,476, 2,553,302, 3,321,012, 3,387,602 and 3,399,664.